|Publication number||US4587042 A|
|Application number||US 06/583,676|
|Publication date||May 6, 1986|
|Filing date||Feb 27, 1984|
|Priority date||Feb 27, 1984|
|Publication number||06583676, 583676, US 4587042 A, US 4587042A, US-A-4587042, US4587042 A, US4587042A|
|Original Assignee||Michael Liva|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Referenced by (7), Classifications (40), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to immersion oils for use in microscopy and specifically relates to an immersion oil system in which the amount of a limited number of basic components may be varied in proportion to each other to create a wide variety of specific oils possessing one or more predetermined physical properties which may be required in a given microscopal application.
The image viewed in a microscope results from light rays, either reflected from or transmitted through the object or specimen to be viewed and then through the optical system of the microscope to the eye or other image sensing or recording devices. The optical system typically comprises the medium in which the object to be viewed is placed, a coverglass, the ambient atmosphere and the glass, plastic or other material which comprises the lens system of the microscope.
It is preferred to eliminate air gaps along a microscopal path of light for several reasons. Relative to glass, plastic, and immersion fluids typically used in the optical systems of microscopes, air or some other low refractive index material limits the angle of light that can enter the objective lens of the microscope, and hence limits the effective aperture and resolving power of the microscope. Replacement of such air gaps with a relatively high refractive index immersion oil thereby effectively increases the effective aperture and resolving power of the system.
Furthermore when light rays pass through one medium to another a certain amount of light is lost due to reflection which occurs at the interface of two different media. The degree of reflection varies with the degree of difference between the indices of refraction of the media through which the light rays pass. Inasmuch as the greatest differences in indices of refraction will typically occur between air (refractive index 1.00) and other light transmissive media (refractive indices typically ranging from about 1.48 to 1.60), it is ideally preferred to compensate for any air gaps which occur between the viewed object and the image sensing or recording device with a medium which is capable of maintaining a substantially uniform index of refraction with all of the other media through which the light will pass.
2. Description of the Prior Art
Immersion oils having predetermined indices of refraction are typically used to fill such air gaps. In addition to having an appropriate index of refraction, an immersion oil may also be required to have specific light absorption, fluoresence, and viscosity properties, depending upon the specific application to which the oil is to be put.
An immersion oil for use in general microscopy as specified by the standards of DIN §5884 should have a principal index of refraction (ne) of 1.518±0.0004 and a principal dispersion factor (Ve) of 44±5. The standards of DIN §5884 further require that an immersion oil should not selectively absorb light having a wavelength in the range extending between about 380 and about 780 nanometers (nm). The standards also require that in normal illumination, an immersion oil should not visibly fluoresce. With respect to viscosity, an immersion oil complying with the standards must also be capable of maintaining the interface between the cover glass and the microscope objective, as well as between the condenser and the microscope slides. In addition the immersion oil must be physically and chemically stable.
Conventional immersion oils typically contain polychlorinated biphenyls (PCBs) which when blended with mineral oil and viscosity adjusting compounds provide a generally useful immersion oil having many of the ideal characteristics described hereinabove. In recent years, however, PCB's have been discovered to be carcinogenic, a hazard to the human environment, and are generally regarded as toxic. Furthermore PCB's are difficult to dispose of after use since they are extremely stable and nonbiodegradable.
The immersion oil for use in microscopy according to the instant invention eliminates the use of PCB's or terphenyls. Thus, the immersion oil of the invention comprises a mixture of a low molecular weight hydrocarbon resin comprising alpha-methyl styrene, diphenyl isodecyl phosphite, and at least one of a mineral oil, a polybutylene, or trilaurlyl trithio phosphite.
Unlike immersion oil mixtures containing PCB's or terphenyls, mixtures of these limited number of components in amounts according to the instant invention do not visibly fluoresce in normal illumination and show no more than weak fluoresence in a darkened room under strong UV irradiation in accordance with the standards of DIN §5884.
Such mixtures according to the invention further comply with conventional immersion oil standards in that they possess desired principal refractive indices, principal dispersion factors, and viscosities.
It is an object of the invention to provide an immersion oil possessing all of the optical properties required for use in general microscopy without the use of PCB's or terphenyls.
It is a further object of the invention to provide an immersion oil having a low autofluorescence in the presence of ultraviolet light.
It is also an object of the invention to provide an immersion oil which can be varied to provide a number of different characteristics and properties.
The immersion oil of the present invention comprises a predetermined mixture of (a) a minor fraction by volume of a low molecular weight hydrocarbon resin (b) diphenyl isodecyl phosphite in the range of about one-third to two-fifths by volume, and (c) at least one of mineral oil, polybutylene, or trilaurlyl trithio phosphite.
The low molecular weight hydrocarbon resin used in the immersion oil preferably comprises a derivative of alpha-methyl styrene having a softening point in the range extending between about 67 and about 88 degrees Centigrade. Low molecular weight hydrocarbon resins most preferred for use in the present invention are those sold under the trademark KRISTALEX 3070 and 3085 by Hercules, Inc., 910 Market Street, Wilmington, Del. These resins are largely comprised of alpha-methyl styrene or derivatives thereof, are water-white, highly color stable, nonpolar, soluble in aliphatic, aromatic, and chlorinated hydrocarbons, and insoluble in alcohols and glycols with limited solubility in nitroparaffins. The KRISTALEX resins have a specific gravity of about 1.06, an acid number less than 1, a Gardner color index less than 1, and a principal dispersion factor in the range extending from about 30 to about 38. The KRISTALEX 3070 and 3085 resins differ in that they have a softening point in the range of about 67°-73° C. and 82°-88° C., a bromine nunber of about 7.8 and 3.0, and a flash point of about 445° C. and 450° C., respectively.
The polybutylenes preferred for use in the invention have an average molecular weight in the range extending from about 570 to about 3,000 grams per mole. Suitable polybutylenes are available from S&S Chemical Company, Chevron, B.P. Chemicals, Cosden Oil & Chemical Co., and Amoco. Preferably, such polybutylenes are selected to have a viscosity (at 100° Fahrenheit) in the range extending from about 3440 to about 900,000 centistokes (cSt).
Typical examples of commercially available polybutylenes suitable for use in the present invention are those sold by Amoco under the designation H-35, H-300E, and H-1900 having the properties listed in Table I.
TABLE I______________________________________ Amoco Polybutylene GradePROPERTY H-35 H-300E H-1900______________________________________Viscosity in Centistokes 74-79 627-675 4069-4382at 98.9° C.Flash Point, °C. 166 227 243Cleveland Open CupAverage Molecular Weight 660 1290 2300(Grams/Mole)Principal Refractive 1.4872 1.4970 1.5042Index______________________________________
The mineral oil preferred for use in the invention is colorless, transparent, insoluble in water or alcohol, free or nearly free from fluorescence in normal illumination and when exposed to ultraviolet light in a darkened room. Such preferred mineral oils have a specific gravity in the range extending from about 0.85 to about 0.91 grams/ml and have a kinematic viscosity of not less than about 38 Centistokes at 100° F.
With respect to the optical properties of the immersion oil of the invention, the index of refraction (ne) and the principal dispersion factor (Ve) of each of the components of the mixture are listed in Table II.
TABLE II______________________________________COMPONENT Ne(±.04) Ve(±7)______________________________________Low Molecular Weight 1.60 34Hydrocarbon ResinMineral Oil 1.48 55Polybutylene 1.50 54Diphenyl Isodecyl Phosphite 1.52 35Trilauryl Trithio Phosphite 1.50 44______________________________________
Each of the preferred embodiments of the immersion oil of the invention complies with the standards of DIN §5884 by having a refractive index in the range extending from about 1.5176 to about 1.5184, a principal dispersion factor in the range extending from about 41 to about 49, and being non-absorptive of 380-780 nm light, non-fluoresent, physically and chemically stable, and capable of maintaining the interface between the cover glass and microscope objective and between the condenser and the microscope slide. These preferred embodiments comprise the components listed in TABLE II in the appropriate amounts listed in TABLE III.
TABLE III______________________________________ APPROXIMATE RANGE INCOMPONENT PERCENT BY VOLUME______________________________________Low Molecular Weight 9-20%Hydrocarbon ResinMineral Oil 0-50%Polybutylene 0-60%Diphenyl Isodecyl Phosphite 30-45%Trilauryl Trithio Phosphite 0-15%______________________________________
Table IV lists four mixtures comprising the preferred embodiments of the immersion oil of the invention in volume percent of each component, each mixture having an index of refraction of about 1.518 and a principal disperson factor of about 44. As shown by Table IV, mixtures of components constituting widely different proportions of the immersion oil mixture may be used for specific applications requiring a predetermined property such as ultraviolet light transmissibility, high or low viscosity, or low cost.
TABLE IV______________________________________Percent by Volume Hydro- Mine- Poly- Diphenyl Trilauryl Carbon ral buty- Isodecyl TrithioProperty Resin Oil lene Phosphite Phosphite______________________________________General Useage 11.8 15.8 29.0 37.3 6.1High UV Trans- 14.0 31.6 00.0 42.1 12.3missibilityHigh Viscosity 9.6 00.0 58.0 32.4 00.0Low Cost 18.5 43.5 00.0 36.2 00.0______________________________________
The specific mixtures listed in Table III are intended to be simply exemplary since many other mixtures can be devised having the most preferred optical characteristics of an index of refraction of about 1.518 and a principal dispersion number of about 44.
In preparing an immersion oil mixture of the invention, the low molecular weight hydrocarbon resin is heated to about 75° Centigrade and then mixed. The heated hydrocarbon resin is then mixed by constant stirring into a proportionate amount of diphenyl isodecyl phosphite, and a proportionate amount of one or more of mineral oil, polybutene, or trilauryl trithio phosphite, as specified above.
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|U.S. Classification||252/582, 252/408.1, 252/1|
|International Classification||G02B21/33, C10M111/00, C10M169/04|
|Cooperative Classification||C10M2223/042, C10M2223/045, C10M2223/04, C10N2240/60, C10M2205/0265, C10N2240/00, C10N2240/50, C10N2240/58, C10N2240/54, C10M2205/026, C10N2240/30, C10M2205/04, C10N2240/22, C10N2240/52, C10N2240/66, C10N2240/56, C10M169/044, C10M2203/06, C10M2203/065, C10M2223/047, G02B21/33, C10N2240/06, C10M2223/0405, C10M2223/083, C10M2223/023, C10M2223/0603, C10M111/00, C10M2205/043, C10M2223/003, C10M2223/0495, C10M2223/103|
|European Classification||C10M111/00, G02B21/33, C10M169/04F|
|Oct 21, 1986||CC||Certificate of correction|
|Dec 5, 1989||REMI||Maintenance fee reminder mailed|
|May 6, 1990||LAPS||Lapse for failure to pay maintenance fees|
|Jul 17, 1990||FP||Expired due to failure to pay maintenance fee|
Effective date: 19900506